What is Emergence Delirium?

Sep 20, 2013

As an anesthesiologistI have answered every question about the risks of anesthesia before procedures. I understand, it can be scary. Including questions like: "my child just had her tonsils out, why is she acting like a child possessed?" "My child just had ear tubes and he woke up and is hitting me and doesn't know who I am. What is going on?" My answer to these questions: Emergence delirium. But before I tell you what that is, let me explain how anesthesia works.

When we have a surgical procedure, we often refer to “going to sleep” for the surgery, and the anesthesiologist is often referred to as “the sleep doctor.” In reality, anesthesia is nothing at all like sleep. If we were to look at what is happening in the brain, the brainwaves we would see on an EEG would not resemble sleep. The child under an anesthetic may look like they are asleep, but that’s where the similarities end.

There are a multitude of drugs that we use to induce and maintain an anesthetic, and unlike medicines that you take at home, these drugs are very potent and also very short acting. So short in fact, that we have to continuously administer them to keep someone anesthetized. Some of the most potent medicines that we use are gasses, and we get them into the body by having the patient breathe them. For children, this is quite convenient because it avoids the all-terrifying shot. In a complex but elegant process, the inhaled medicines pass through the lungs, into the blood stream, and then into the brain, where they take their effects and induce unconsciousness.

At this point, surgery commences and we get down to why you brought your child to the hospital in the first place. Once the surgery is over it’s time to “wake the patient up.” The anesthesiologist will have been preparing for this moment for quite awhile and has been administering an appropriate amount of pain medicines and begins titrating off the anesthesia gasses so that the patient emerges from anesthesia within a few minutes of the surgery’s end.

That amazing process of putting the child “to sleep” now reverses. The body doesn’t metabolize the anesthetic gasses in the same way as, say, an antibiotic that your pediatrician may prescribe for strep throat. So, rather than relying on your body to break down the drugs, our anesthetic gasses are exhaled more-or-less unchanged. The drugs dissolve out of the brain and back into the blood, and then into the lungs. This is one reason why your daughter’s breath smells so strange after surgery. Then, it’s off to the recovery room, where your daughter will gradually emerge from anesthesia, oftentimes actually slipping into a true sleep. After a short period of time, we'll gently wake her up from her nap, and reunite her with her family; she may be a little sleepy, or a little groggy at first, but in a few hours, she’ll be as good as new.

That’s how it’s supposed to work, and most of the time, that’s exactly how it works. But people (and children in particular) do not always emerge from anesthesia in such a gentle fashion. Sometimes, children wake up acting like they are possessed. They are irritable, combative, inconsolable, or uncompromising. They do not recognize familiar objects or people. Oftentimes the child is thrashing around in bed, eyes closed, incoherent, kicking and crying. These are symptoms of emergence delirium, sometimes also known as emergence excitation or emergence agitation, which was first reported in the early 1960’s. It’s a shocking sight, and for those not previously initiated to the event, can be quite frightening.

The condition has been observed after anesthetics of all types: from ether, the first anesthetic, to our newest and greatest medicines. Unfortunately, no one is completely certain why this phenomenon occurs. It ranges in incidence from 10-80%. Such a broad range of incidence exists because it’s been difficult for us to come up with a set of criteria to describe it. Is a child crying in the recovery room because he is suffering from emergence delirium, in pain, missing Mom, or does he just really not like his IV?

There is a component of pain in emergence delirium, but we’ll also often see it after an MRI, which causes no pain. Some surgeries have a higher incidence as well; these include tonsil and adenoidectomies, eye surgery, and middle ear surgery. There is a component of unfamiliarity, but we often also see it when the parents are present in the recovery room. Children and parents who are especially anxious prior to surgery are also at higher risk of having the child develop emergence delirium in the recovery room. But we sometimes also see it even if we pre-medicate a child with a sedative or anti-anxiety medicine prior to coming into the operating room. Children aged 2-5 years seem to have a higher incidence of emergence delirium. There are other child-specific characteristics that may also be associated with emergence delirium, but again, those are harder to define and therefore study.

So, why does emergence delirium happen? Honestly, nobody really knows. Some speculate that it has to do with the immaturity of the brain, others with the rapidity with which the anesthesia drugs leave the brain. Others point to the surgery itself, or the temperament of the child. This all leaves us in a quandary. If we don’t know why it happens, how can we predict it, and how can we prevent it? Multiple different anesthetic techniques and medications have been tried. And they have all been found to be helpful, although maybe not to the extent we would want, and definitely not to the point where the incidence is 0%.

The good news is that emergence delirium is not permanent, and does not cause any long-term side effects. In most cases, we tend to ride out the storm, which passes after 5-15 minutes. That’s not to say that harm cannot occur during an episode of emergence delirium. Such a child usually requires extra hands to help the recovery room nurse keep the patient from pulling out IV catheters, dressings, or drains. We also have to ensure that the child doesn’t injure himself on the bed or harm the surgical site.

If we are faced with an especially robust bout of emergence delirium, we will give additional sedatives. I think of this sort of like a soft reset for your phone or computer. We quickly put the child back “to sleep” and then let them “wake up” again. That almost always works. Reuniting children with their parents tends to help as well.

Although I have no scientific data to back this up, I feel that there is a fundamental difference between an adult emerging from anesthesia and a child. When an adult emerges from an anesthetic they are confused and disoriented. They look around, see that nobody looks like they are going to kill them, and they all seem friendly enough. Then, some part of them remembers that “oh yeah, I came in for surgery.” As a child emerges from anesthesia, they too are confused and disoriented. But in this case, all they know is that, this nurse isn’t “Mom.” Emergence delirium is real, and it’s frightening to witness. While we may not completely understand how it happens, we are prepared, and we are adept at treating it - whether with sophisticated medications or a caring touch, or the irreplaceable comfort of Mom or Dad.

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Marco Corridore, MD

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